package com.android.ming.ui.widget;

import android.content.Context;
import android.support.v4.widget.SwipeRefreshLayout;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.widget.AbsListView;
import android.widget.ListView;

import com.android.ming.R;

/**
 * Created by YO on 2016/8/16.
 */
public class RefreshLayout extends SwipeRefreshLayout implements AbsListView.OnScrollListener {

        /**
         * 滑动到最下面时的上拉操作
         */

        private int mTouchSlop;
        /**
         * listview实例
         */
        private ListView mListView;

        /**
         * 上拉监听器, 到了最底部的上拉加载操作
         */
        private OnLoadListener mOnLoadListener;

        /**
         * ListView的加载中footer
         */
        private View mListViewFooter;

        /**
         * 按下时的y坐标
         */
        private int mYDown;
        /**
         * 抬起时的y坐标, 与mYDown一起用于滑动到底部时判断是上拉还是下拉
         */
        private int mLastY;
        /**
         * 是否在加载中 ( 上拉加载更多 )
         */
        private boolean isLoading = false;

        /**
         * @param context
         */
        public RefreshLayout(Context context) {
                this(context, null);
        }

        public RefreshLayout(Context context, AttributeSet attrs) {
                super(context, attrs);

                mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();

                mListViewFooter = LayoutInflater.from(context).inflate(R.layout.listview_footer, null,
                        false);
        }

        @Override
        protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
                super.onLayout(changed, left, top, right, bottom);

                // 初始化ListView对象
                if (mListView == null) {
                        getListView();
                }
        }

        /**
         * 获取ListView对象
         */
        private void getListView() {
                int childs = getChildCount();
                if (childs > 0) {
                        View childView = getChildAt(0);
                        if (childView instanceof ListView) {
                                mListView = (ListView) childView;
                                // 设置滚动监听器给ListView, 使得滚动的情况下也可以自动加载
                                mListView.setOnScrollListener(this);
                                Log.d(VIEW_LOG_TAG, "### 找到listview");
                        }
                }
        }

        /*
         * (non-Javadoc)
         * @see android.view.ViewGroup#dispatchTouchEvent(android.view.MotionEvent)
         */
        @Override
        public boolean dispatchTouchEvent(MotionEvent event) {
                final int action = event.getAction();

                switch (action) {
                        case MotionEvent.ACTION_DOWN:
                                // 按下
                                mYDown = (int) event.getRawY();
                                break;

                        case MotionEvent.ACTION_MOVE:
                                // 移动
                                mLastY = (int) event.getRawY();
                                break;

                        case MotionEvent.ACTION_UP:
                                // 抬起
                                if (canLoad()) {
                                        loadData();
                                }
                                break;
                        default:
                                break;
                }

                return super.dispatchTouchEvent(event);
        }

        /**
         * 是否可以加载更多, 条件是到了最底部, listview不在加载中, 且为上拉操作.
         *
         * @return
         */
        private boolean canLoad() {
                return isBottom() && !isLoading && isPullUp();
        }

        /**
         * 判断是否到了最底部
         */
        private boolean isBottom() {

                if (mListView != null && mListView.getAdapter() != null) {
                        return mListView.getLastVisiblePosition() == (mListView.getAdapter().getCount() - 1);
                }
                return false;
        }

        /**
         * 是否是上拉操作
         *
         * @return
         */
        private boolean isPullUp() {
                return (mYDown - mLastY) >= mTouchSlop;
        }

        /**
         * 如果到了最底部,而且是上拉操作.那么执行onLoad方法
         */
        private void loadData() {
                if (mOnLoadListener != null) {
                        // 设置状态
                        setLoading(true);
                        //
                        mOnLoadListener.onLoad();
                }
        }

        /**
         * @param loading
         */
        public void setLoading(boolean loading) {
                isLoading = loading;
                if (isLoading) {
                        mListView.addFooterView(mListViewFooter);
                } else {
                        mListView.removeFooterView(mListViewFooter);
                        mYDown = 0;
                        mLastY = 0;
                }
        }

        /**
         * @param loadListener
         */
        public void setOnLoadListener(OnLoadListener loadListener) {
                mOnLoadListener = loadListener;
        }

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {

        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
                             int totalItemCount) {
                // 滚动时到了最底部也可以加载更多
                if (canLoad()) {
                        loadData();
                }
        }

        /**
         * 加载更多的监听器
         *
         * @author mrsimple
         */
        public static interface OnLoadListener {
                public void onLoad();
        }
}